I understand you can't go in to details about your pain, but some information is necessary to understand why you might need EMG or MRI.
Do you have foot pain, yet no objective symptoms on XRay?
An MRI is magnetic Resonance imaging. It can be useful in detecting any neuroma's. EMG is a test of conduction velocity of your nerves.
It is used to detect any neurological abnormality, such as an impinged nerve, nerve entrapment, peripheral neuropathy. Some types of nerve damage will not show up on an EMG.
If you are diabetic and having any foot problem you should see a neurologist.
It sounds as if you are searching for some answers. You can certainly benefit from this group because many have first hand knowledge of tests and conditions.
If you can leave a little more info on your situation, ie post-surgery complications, pain that physician cannot diagnose, this group might be able to offer insight on further testing or care.
Knowing what it is you are trying to identify helps define the role of MRI xrays and EMG.
Good luck in your recovery.